The Solfeggio tuning forks are available with or without weights. The unweighted set is used around the body and by the ears. The weighted Solfeggio is used on the body and by the ears.
If you want to work with these frequencies, then I recommend both sets however if price is an issue, start with the unweighted set the get the weighted set soon after.
As mentioned in a previous post, the Solfeggio frequencies are great for emotional healing and personal awareness. These frequencies were made popular by Dr. Puelo in his book, The Healing Codes of the Biological Apocalypse. In it, Dr. Puleo recognized in the Old Testament how the numbers 3, 6 and 9 were used for healing. The Solfeggio tuning fork frequencies are based on these numbers. For example, one of the frequencies are 417hz; 4+1+7=12, 1+2=3. There are plenty of articles on numerology out there if you would like to learn more about numerology.
The frequencies of the unweighted set are not the same as the weighted set but the weighted set is still based on the numbers 3, 6 and 9. The proper weighted Solfeggio frequencies were given to me by Randy Masters, a mathematician, musician, sacred geometrist and generally, someone who you just like to be around. It has a different mainly because they are placed on the body and anyone working with the Solfeggio frequencies will not be disappointed with the weighted set.
If you are uncertain of the difference between the weighted and unweighted tuning fork, then take a look at some short educational videos on YouTube. Search for the Omnivos Therapeutics channel or on How to Use a Weighted Tuning Fork and How to Use an Unweighted Tuning Fork.